DECLARE @ClaimDetail TABLE (id INT IDENTITY(1,1),modcode CHAR(2))
INSERT INTO @ClaimDetail (modcode) VALUES ('HO')

DECLARE @FeeTable TABLE (id INT IDENTITY(1,1), modcode CHAR(2), fee MONEY)
INSERT INTO @FeeTable (modcode,fee) VALUES ('HO',2.00),(' ',1.75)


SELECT
	CD.modcode AS CDModCode,
	CASE 
		WHEN (SELECT F.Fee FROM @FeeTable AS F WHERE F.modcode = CD.modcode) IS NULL THEN (SELECT F.Fee FROM @FeeTable AS F WHERE F.modcode = '')
		ELSE (SELECT F.Fee FROM @FeeTable AS F WHERE F.modcode = CD.modcode)
	END AS Fee
FROM
	@ClaimDetail AS CD
	
	